Step By Step: Rebuild A Turbo

We’ve carefully disassembled this Garrett TP-38 turbo, making sure to clean all the parts before reassembly.

2/16

Turbocharger journal bearings are made from a soft material, the surfaces are the first to show damage. An inspection of the original bearings (two outer parts) showed no wear from dirty oil.

3/16

Inspection of the thrust collar and thrust bearing (C-shaped one) show these are also good. Oil flows through the canal (A) in the thrust bearing shown in the picture, and if there was a problem it would show up on the raised pads toward the center (B). Scorched pads indicate heat issues, while line grooves show dirty oil. Carefully remove and inspect the piston ring in the collar (C).

4/16

With the piston ring removed from the turbine wheel’s hub area, put the thrust collar and compressor wheel on the shaft and tighten. This particular turbo’s compressor wheel has a built-in threaded nut. Since we’re talking aluminum threads here, we’ll want to tighten to 50 lb-in (not 50 lb-ft!). We’re numbering 1 through 4 with a pen on the back of both the compressor wheel and turbine so that we’ll know where to grind if needed for balancing.

5/16

Not having access to a balancing machine makes rebuilding your own turbo inadvisable because you can do everything perfectly—only to have the turbo fail due to imbalance. The machine’s strobe light will show the heavy spots that will need grinding, and the numbers we made beforehand will make it easier to pinpoint those problem areas.

6/16

Use patience and avoid gouging while grinding the compressor and turbine wheels. If too much is ground down, you’ll be chasing heavy spots all day. Slow and steady wins this race.

7/16

Use a permanent marker to make an index point between the compressor wheel and the shaft. This way you can assemble the wheels exactly how they were when you balanced them.

8/16

Make sure that the piston-ring gaps of both the thrust collar and the turbine hub are facing straight up in the sky when installed on the engine. By doing so, you make sure that as the turbo fills with oil during operation, the gap does not cause a leak.

9/16

After making sure the thrust collar and thrust bearing are both seated correctly with the piston ring in the proper orientation, install the backplate with four bolts, tightening evenly around.

10/16

Lube and drop in the bearings, making sure that they seat all the way in.

11/16

Install the turbine piston ring on the hub area. Lube the piston-ring groove and journal area on the shaft.

12/16

Install the shaft into the housing through the bearings. Make sure there are no obstructions, and the two go together smoothly.

13/16

Using a vice with the nut at the end of the turbine wheel secured firmly in place, install the compressor wheel. Again, this compressor wheel is threaded. Spin the wheel until it is seated firmly. Torque to 50 lb-in.

14/16

With your center housing rotating assembly (CHRA) together, squirt some oil into the oil inlet and firmly hold the unit with one hand. With the other hand, push downward on the compressor wheel while turning the shaft. There will be slight movement side to side, but as the oil starts to fill in the gaps in the surfaces, the lateral play will diminish but not disappear. There should be no “rough spots” or hang-ups. If the assembly gets hung up, then there might be an issue with the turbine side or compressor piston ring’s seating.

15/16

Make sure the backplate’s O-ring is installed. A little bit of lube on the O-ring can help in installation. Install the CHRA into the compressor housing straight in, making sure the wheel doesn’t hit the side of the compressor bore. Being sloppy can bend the compressor wheel’s blades, which would ruin everything you’ve done.

16/16

Install the turbine housing. Repeat step 14 by pressing down on the tip of the compressor wheel and turning at the same time as a final check to see if there is any rubbing or hang-ups. If everything checks out and the assembly moved freely, then reinstall on engine. Congrats, you just rebuilt your turbo!